Piston locking means for fluid actuated jacks



Jan. 20, 1948. B. N. ASHTON ETAL PISTON LOCKING MEANS FOR FLUID ACTUATED JACKS Filed Nov. 10, 1944 S N a wm wm ...,N/ MI WQ .mw Q JD w M Y B H vm. Q l 11117/ y u f Ihllmn SvVVV/y/ NW. h. GWW une@ m www mm mw mv mv mm f nm 6 mm QM SQ m ,dwg A Tron/verf Patented Jan. 20, 1948 PISTON LOCKING MEANSV FOR FLUID ACTUATED JACKS Benjamin N. Ashton, Kingston, and Nelson Kling,

Great Neck, N. Y., assignors to Electrol Incorporated, Kingston, N. Y., a corporation of Delaware Application November 10, 1944, Serial No. 562,832

4 claims. 1

This invention relates to fluid-actuated motors or jacks of the cylinder and piston type and it relates particularly to mechanisms for locking the pistons of such fluid-actuated jacks at one or both ends of the piston stroke.

This is a continuation-impart of-our application Serial No. 478,574, iiled March 9, 1943, now Patent No. 2,393,962, dated February 5, 1946.

An object of the present invention is to provide locking means for the pistons of fluid-actuated jacks in which the locking means is effective only at the end of the stroke of the piston and does not exert frictional forces or Wearing stresses on the piston or cylinder during the movement of the piston in the cylinder.

Another object of the invention is to provide locking means for the pistons of duid-actuated jacks in which the locking means automatically locks the piston to the cylinder at at least one end of its stroke and in which the locking means can be released either manually or by uid pressure to permit movement of the piston to the cpposite end of its stroke.

Other objects of the invention will become apparent from the following description of typical forms of devices embodying the present invention.

In accordance with the present invention, we have provided the piston and the cylinder of a fluid-actuated jack with recesses for reception of one or more locking members such as, for example, balls when the piston is at one end of the cylinder. Cooperating with the locking members or the balls is a piston member that moves relatively to the piston and the cylinder to' enter one of the recesses at the end of the piston stroke, only, to force the locking member into the recesses. This piston member can be retracted by means of i'luid pressure to release the piston for movement relatively to the cylinder.

Sometimes the means for supplying fluid pressure, for example a hydraulic system of an airplane, becomes disabled and for that reason it is unable to supply uid pressure for unlocking and advancing the piston. If this occurs, for example, when the hydrau.ic jack associated with retractable landing gear is in its retracted position, it is impossible to lower the landing gear. Therefore, the present invention includes mechanism associated with the piston locking mechanism whereby the locking mechanism can Ibe released manually in order to permit movement of the piston under gravity or other forces.

-For a better understanding of the present invention, reference may be had to the accompanying drawings, in which,

Figure 1 is a view in longitudinal section and partially broken away of a typical form of locking mechanism embodying the present invention;

Figure 2 is a view in longitudinal section of a modied form of hydrauic jack including fluid responsive and manually operable mechanism for locking and unlocking the piston; and

Figure 3 is a view in cross section taken on line 3-3 of Figure 2.

Figure l of the drawings illustrates one form of piston lock embodying the invention. In this device, a cylinder I0 is provided with a threaded end portion Illa for receiving an internally threaded cap II of generally cup-like form. The cap II is retained in sealing engagement with the cylinder I0 by means of a threaded ring I2 and a sealing ring I3. The cap II is provided with a coupling I4 which communicates with the interior of the cylinder I0 through an aperture Illa so that fluid under pressure can be admitted in the cylinder.

As illustrated, the cap II is provided with a cup-shaped member I5 secured to the end of the cap in any suitable way, such as by the set screw I5. The member I5 is provided with one or more apertures Ilia for receiving the locking balls Il. The apertures I5a taper in diameter from slightly larger than the diameter of the balls I1 at their outer periphery to slightly less than the diameter of the balls I'I at their inner periphery so that the balls cannot fall into the cylinder.

The side wall or flange of the member I5 is spaced from the cylinder l0 a suicient distance that the balls I'I can be retracted fully, but cannot escape from between the member I5 and the cylinder I0.

A piston I8 is slidably mounted in the cylinder I0. This piston may include a cylindrical core member I9 having a centrally disposed ilange I9a and oppositely threaded `reduced end portions I9b and I9c. The center portion of the mem-ber I9 is adapted to receive a pair of annular piston members 2D and 2I. The member 2| includes a disc-like portion 2Ia which is sealed to the core member I9 by means of a sealing ring 22 and is provided with an axially projecting ange 2lb that engages the wall of the cylinder I0. The member 2I also includes an oppositely directed flange member 2Ia slidably engaging the body of the core member I9 and is provided with a plurality of bores 2Id for receiving the coil springs 23.

The ange member 2Ia is of less diameter than locking mechanism can be provided with only one locking member, if desired. Therefore, the forms of the invention described above should be considered as illustrative of the invention and not as limiting the scope of the following claims.

We claim:

1. A piston lock for fluid actuated jacks comprising a cylinder having an internal recess at one end thereof, a piston slidable in said cylinder having an external recess adjacent one end thereof, said recesses being aligned when the piston is at one end of its stroke, a locking member supported loosely in one of said recesses and movable partially into both of said recesses when they are aligned, a piston member slidable axially of said cylinder and said piston for entering said one recess only near the end of said stroke to engage and force said locking member partially into both of said recesses to lock said piston to said cylinder, means normally urging said piston member toward said one recess, said piston member being displaceable axially by fluid pressure against the action of said urging means to release said piston for movement to the opposite end of its stroke, a tubular piston releasing member movably mounted in said cylinder adjacent to said internal recess having a portion for moving said piston member when said piston is locked to said cylinder, a coupling communicating with said tubular piston-releasing member for introducing fluid into said cylinder to displace said piston member to release said piston for movement to said opposite end of its stroke, and manually operable means for moving said piston releasing member to displace said piston member axially and release said piston for movement to said opposite end of its stroke.

2. A piston lock for fluid actuated jacks comprising a cylinder having a member provided with an apertured internal flange member adjacent to one end of said cylinder, said ange being spaced radially from the side of said cylinder to provide an internal recess, a piston slidable axially of said cylinder having a recess in its exterior adapted to enter said ilange and move into alignment with the apertures in said flange, locking members loosely mounted in said apertures movable partially into said recess in said piston, a piston member slidable on the exterior of said piston and having a flange adapted to enter the space between said cylinder and said flange member to engage and urge said locking members into the recess in said piston, spring means carried by said piston normally urging said piston member axially toward said flange member, means for introducing duid under pressure into said cylinder adjacent opposite ends thereof, said piston member being movable axially away from said ilange member and relatively to said piston to release said piston in response to the pressure of the uid introduced into said cylinder adjacent said one end, a shaft rotatably mounted in said one end of said cylinder and extending transversely of said cylinder, means for rotating said shaft, and a cam member on said shaft adjacent to said flange member for moving said flange out of engagement with said locking members upon rotation of said shaft.

3. A piston lock for fluid actuated jacks comprising a cylinder having a member provided with an apertured internal flange adjacent to one end of said cylinder, said flange being spaced radially from the side of said cylinder to provide an internal recess, a piston slidable axially of said cylinder having a recess in its exterior adapted to enter said flange and move into alignment with the apertures in said ilange, locking members loosely mounted in said apertures movable partially into recess in said piston, a piston member slidable on the exterior of said piston and having a flange adapted to enter the space between said cylinder and said flange member to urge said locking members into the recess in said piston, spring means carried by said piston normally urging said piston member axially toward said ilange member, means for introducing iluid under pressure into said cylinder adjacent opposite ends thereof, said piston member being movable axially away from said flange member and relatively to said piston in response to the pressure of the fluid introduced into said cylinder adjacent said one end to release said piston, a manually actuated cam member movably mounted in said cylinder adjacent to said one end, and means slidable axialli7 of said cylinder in response to movement of said cam member for displacing said piston member axially to release said piston.

4. A fluid actuated jack comprising a cylinder having an internal recess at each end thereof, a piston slidable axially of said cylinder and having external recesses at opposite ends thereof, the recess at one end of the cylinder being aligned with the recess at one end of said cylinder when the piston is at said one end of said cylinder, and the recess at the other end of said piston being aligned with the recess at the other end of the cylinder when the piston is at said other end of said cylinder, locking members supported loosely in said internal recesses at said one and other ends of said cylinder, a pair of piston members slidable relatively to and mounted on the exterior of said piston, means interposed between said piston members normally urging them apart, means on one of said piston members for entering said internal recess at said one end, means on the other piston member for entering said internal recess at said other end to urge said locking members into the aligned recesses when the piston is at one end or the other ends of said cylinder, said piston members being displaceable axially by fluid pressure against the action of said urging means to release said piston for movement axially of said cylinder.

BENJAMIN N. ASHTON. NELSON KLING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,163,982 Mercier June 27, 1939 2,221,121 Wallace Nov 12, 1940 2,393,962 Ashton et al Feb. 5, 1946 FOREIGN PATENTS Number Country Date 493,471 Great Britain Oct. 10, 1938 341,511 Italy July 27, 1936 

